1. Field of the Invention
Embodiments of the present invention relate to inverted emulsion fluids for use in oil/gas field applications and to methods for making and using the fluids.
More particularly, embodiments of the present invention relate to inverted emulsion fluids for use in oil/gas field applications, where the fluids include at least one novel secondary emulsifying agent and to methods for making and using the fluids and the secondary emulsifying agents.
2. Description of the Related Art
In inverted emulsion systems, such as inverted emulsion drilling fluid (IEDF) systems, water is the internal phase or discontinuous phase, while oil is the continuous phase. Inverted emulsion systems are formulated using primary and secondary emulsifiers. The systems can also include other additives as well. Primary emulsifiers are used to reduce interfacial tension between the liquid phases and hence make the internal phase dispersible, while secondary emulsifiers consolidate stability of the dispersed phase or stability of the emulsion. In inverted emulsion systems, stability is always an issue. Stability of such systems is generally determined by measuring electrical stability (ES). The voltage required to destabilize the dispersed phase is recorded as the ES value. The higher the ES value, the more stable the emulsion. Not only is a high ES needed for IEDF systems, but the emulsifiers also should maintain rheological properties of the systems to improve functionality.
In the prior art, the general approach for inverted emulsion fluid is to use fatty acid soaps, like calcium oleate. Moreover, amines, hydroxylamine, amides, sulfonates or sulfates, or similar compounds have been used either neat or as mixtures for producing inverted emulsion fluids.
Although numerous inverted emulsion fluid systems have been disclosed and implemented, there is still a need in the art for secondary emulsifiers that are effective and efficient at low dosage and offer thermally stable inverted emulsion fluid systems.